Covered wire



March 11, 1941. J.' J. KEYES 2,234,560

COVERED WIRE Filed Nov. 16, 1938 I 4T /2- Sid/Die 6705s F2567.'

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Y Patented Mar. 11, 1941 UNITED STATES PATENT OFFICE inghouse Electric d: Manufacturing Company,

East Pittsburgh, Pa.. a corporation of Pennsylvania Application November 16, 1938, Serial No. 240,701

8 Claims.

flhis invention relates to wire having a covering of fibrous material.

Heretofore, electrical conductors have been produced having many different types of insu- I lating coverings. In most of these cases it has been necessary to employ coverings containing organic material or which were not resistant to high operating temperatures.

An object of this invention is to provide a wir l having an inorganic covering.

Another object of this invention is to provide a wire having a covering of inorganic material disposed about the wire in diierent forms whereby each form functions to best advantage in maintaining the wire completely insulated.

A more specic object of this invention is to utilize glass ilbers of both the staple and continuous iilament types as the covering for wire, the staple type iibers being adjacent the wire and providing a cushion or yielding layer forrthe continuous filament type of fibers to facilitate the making and maintenance of a completely insulated conductor under operating conditions.

A further object of this invention is to provide a wire having a covering formed from substantially alkaline-free glass bers of the staple and continuous filament types applied thereto in a predetermined manner and coated and impregnated with an insulating varnish.

o other objects of this invention win become apparent from the following description when takenA in conjunction with the accompanying drawing, inwhich u Figure 1 is an elevational view, greatly exaggerated, of a covered wire embodying this invention;

Fig. 2 is a sectional view taken along the line lI-II of Fig. 1; o F18. 3 is an elevational view of another embodiment of this invention; and

Fig. 4 is a sectional view taken along the line IV-IV of Fig. 3.

Referring to Figs. 1 and 2 of the drawing, this 5 invention is illustrated as embodying the wire I0 covered with an inorganic material. The inorganic material employed as the covering is formed from glass bers which are nonhygrolcopic and, as compared to asbestos and other u materials employed heretofore, have no metallic particles, higher dielectric strength, lower insulation losses, better heat conductivity, better space factor and are more uniform in coverage and thickness. u In accordance with the invention, the covering of inorganic material on the wire is formed from a plurality of layers of material having the same composition but which are in diiferent form. The preferred inorganic material utilized is -glass formed into very fine bers. It has only recently 5 been commercially possible to spin the glass into fibers suillciently ne to permit their use as embodied in this invention. These iibers have a diameter of .00025 inch or less and in this state are not as brittle as the heavier bers.

In manufacturing the glass bers utilized in this invention, two processes are now generally employed. These are known as the continuous iilament process and the staple fiber process. In the continuous filament process, glass of predetermined composition is melted and continuous iilaments, usually 102 in number, are drawn from the melt onto a spool after which the filaments are worked into yarns, tapes, etc., in a manner similar to the making of rayon. As distinguished from the continuous iilament process, the staple fibers are produced from the molten glass by drawing them from the melt by means of a blast of steam applied to the glass as it leaves the reservoir, thereby breaking the glass into line fibers of diiierent length. As a general rule, the staple bers are not over from 10 to 12 inches in length, the average being about 6 to 8 inches. The staple fibers may be worked into yarn in a manner similar to the process in making cotton yarn.

The glass which it is preferred to utilize in this invention is one which is substantially alkalinefree, containing not over 5% of soda. If a higher soda content is present, the glass has poor stability under changing humidity conditions, the moisture encountered drawing the alkali from the glass and causing the iibers to quickly deteriorate. This poor stability of the higher alkaline glass can, however, be overcome if an impregnating material which contains a weak or- 40 ganic acid is employed in conjunction with the glass, the Weak organic acid functioning to neutralize the alkalinity of the glass.

In covering the wire i0, a. layer I2 of the unwoven staple fibers is formed around and over the 5 wire in thread or yarn form. This layer may also be felted or spun on to the wire direct from the glass reservoir or furnace or in a manner comparable to the known methods of applying asbestos to wire, as in the form of roving. As formed around the wire, the layer I2 is soft and fluffy having a certain amount of resiliency under shock. These staple bers are, however, not satisfactory as a nnished covering on the wire u since they do not have the desired strength and resistance to abrasion. Further, since the bers are relatively short, the surface of the layers l2 has a very fuzzy appearance because of the ends of the fibers projecting therefrom.

In order to provide a smooth finish to the conductor covered with the staple bers, and to provide increased resistance to abrasion, a layer I4 of the glass fibers of the continuous filament type is employed. 'Ihis type has the strength necessary for maintaining itself as an integral covering and when applied around the layer of staple bers covers the loose fuzzy ends. 'I'he covering of the continuous filament fibers may be formed either by helically Winding the yarn directly over the staple bers or by applying the continuous filament bers thereto in the form of tape, braid, sleaving or any other suitable form.

The two layers of glass bers in different forms cooperate with each other in giving a highly desirable article. Since the vlayer of the staple ber is somewhat resilient, it acts as a cushion or yielding layer for the continuous filament layer which is inherently more brittle in bulk than the staple ber, permitting bending of the covered Wire without damage to the outer covering. In service it is found that the layer of staple bers prevents the breaking or cutting of the outer layer formed from the continuous laments by abrasion or pounding when the covered Wire is employed in industry. Because the outer covering is of the vcontinuous lament, it gives a covering of high strength which has a very smooth appearance and functions to retain the comparatively short staple bers of the inner layer in position about the wire- Both the staple fibers and the continuous bers are inorganic materials which have an exceedingly high dielectric strength and high heat conductivity and which, because of their size, may be utilized as very thin layers over the wire.

In service it is sometimes desirable to utilize an impregating compound or varnish in conjunction with the ,inorganic glass ber coverings of this invention. Different types of impregnating compounds may be utilized depending upon the types of service in which it is desired to employ the covered wire. Suitable impregnating compounds or varnishes are those known to the trade as oxidizing oil varnishes, oleoresinous varnishes or the impregnating insulating heat reactive types, such as the phenol formaldehyde and alkyd type resins or vinyl acetate. The use of such an impregnating compound or varnish is illustrated in Figs. 3 and 4 in which I6 indicates a layer of the impregnating material formed on the covering of the continuous lament bers, vit being understood that this impregnating material penetrates the interstices of the glass bers of both the inner an outer layers forming the glass covering. The oxidizing oil and oleoresinous varnishes are to be preferred where the glass has a content of up to5% of soda, since they will form weak organic acids to neutralize the small amount of alkali which may be encountered with such glass. Where an impregnating material is used, it is preferred that the impregnated and covered conductor be subjected to suicient heat to so x or set the impregnating material that it is substantially stable under normal operating conditions.

Although this invention has been described with reference to a particular embodiment thereof, it is, of course, not to be limited thereto except insofar as is necessitated by the prior art and the scope of the appended claims.

I claim as my invention:

1. An article of manufacture comprising a wire and a covering therefor, said covering comprising an inner resilient layer o! unwoven substantially alkaline-free glass bers of the staple type applied directly around and over the wire and an outer layer of substantially alkaline-free glass fibers of the continuous type, said outer layer being in the form of a braid of the continuous bers and being applied directly around and over the inner resilient layer of glass bers;

2'. An article of manufacture comprising a wire and a covering therefor, said covering comprising an inner layer of unwoven substantially alkalinefree glass fibers of the staple type adjacent the wire and an outer layer of substantially alkalinefree glass bers of the continuous type, the layer of unwoven glass bers forming a resilient backing for the outer layer, and a coating of insulating varnish on the outer layer of glass bers, the insulating varnish impregnating the inner and outer layers of glass bers of different types.

3. An article of manufacture comprising a wire and a covering therefor, said covering comprising an inner resilient layer of unwoven substantially alkaline-free glass bers of the staple type applied directly around and over the wire and an outer layer of substantially alkaline-free glass bers of the continuous type, said outer layer being in the form of a braid of the continuous bers and being applied directly around and over the inner resilient layer of glass bers, and a coating of insulating varnish on the outer layer of glass bers, the insulating varnish impregnating the different inner and outer layers of glass bers.

4. An article of manufacture comprising a wire and a covering therefor, said covering comprising an inner layer of unwoven substantially alkalinefree glass bers of the staple type applied directly around and over the wire and an outer layer of substantially alkaline-free glass fibers of the continuous type applied directly over and around the inner layer, the bers of the inner and outer layers having an average diameter of not more than .00025 inch, the inner layer of staple fibers being suilciently resilient to permit bending of the 'sovered wire without damage to the outer cover- 5. An article of manufacture comprising a Wire and a covering therefor, said covering comprising an inner layer of unwoven substantially alkalinefree glass bers of the staple type applied directly around and over the wire and an outer layer of substantially alkaline-free glass bers of the continuous type applied directly around and over the inner layer, the outer layer being in the form of yarn helically Wound about the unwoven staple bers of the inner layer for retaining them in position about the Wire.

6. An article of manufacture comprising a'wire and a covering therefor, said covering comprising an inner layer of unwoven substantially alkalinefree glass bers of the staple type applied directly around and over the Wire and an outer layer of substantially alkaline-free glass bers of the continuous type applied directly around and over the inner layer, the outer layer being in the form of yarn helically wound about the unwoven staple bers of the inner layer for retaining them in position about the wire, and an electrically insulating material associated with and disposed to ll the interstices of the brous layers,

7. An article of manufacture comprising a wire and a covering therefor, said covering comprising an inner layer of unwoven substantially alkaline- 2,234,560 lfree glass fibers of the staple type adjacent the wire and an outer layer of substantially alkalinefree glass bers of the continuous type, the layer of unwoven glass bers forming a resilient backing for the outer layer. v

8. An article of manufacture comprising a conductor and a, covering therefor, said covering comprising an inner layer of unwoven glass bers of the staple type adjacent the wire and an outer 10 layer of glass bers of the continuous type. the

layer of unwoven glass iibers forming a. resilient bacldng for the outer layer, the glass bers of each of the inner and outer layers containing not more than 5% of soda thereby being substantially alkaline-free, and a. coating of insulating varnish on the outer layer of glass fibers, the insulating varnish being an oleoresinous varnish and impregnating the inner and outer layers of glass bers of diierent types.

JOHN J. KEYES.

DISCLAIMER 2,234,560.-J0hn J. Keyes, Edgewood, Pa.. COVERED WIRE. Patent dated March 11, 1941. Disclaimer led January 20, 1945, by the assignee, Westinghouse Electric cf: Manufacturing Company. Hereby enters this disclaimer to claims 2, 4, and 7 of said patent.

[Oficial Gazette February 20, 1955.]

DISCLAIMER 2,234,560r-Jokn J. Keyes, Edgewood, Pa. COVERED WIRE. Patent dated March 11, 1941. Disclaimer filed January 20, 1945, by the assignee, Westinghouse Electric cf: Manufacturing Company.

Hereby enters this disclaimer to claims 2, 4, and 7 of said patent.

[Oficial Gazette February 20, 1.955.] 

